Monday 12 September 2011 19.10 EDT
First published on Monday 12 September 2011 19.10 EDT

A series of clashes between high-profile MPs from the main political parties will take place at the next general election, after the boundary review unveiled bigger than expected changes to England's parliamentary constituencies.

As anxious Conservatives warned their whips on Monday night of a rebellion against the changes, which will have to be approved by the Commons, MPs across the house were ready for bruising battles.

Vince Cable leads a list of senior Liberal Democrat MPs who face major changes to their constituencies. Large chunks of Cable's Twickenham will be joined with Richmond, setting up a possible clash at the election between the business secretary and Zac Goldsmith, Tory MP for Richmond Park. Cable may decide to stand in the new seat of Teddington and Hanworth which takes in much of his old seat of Twickenham.

The main changes in the review by the Boundary Commission for England, which is designed to reduce the size of the commons from 650 MPs to 600, include:

• A clash between two rising stars of the Labour: shadow justice secretary Sadiq Khan and shadow business minister Chuka Umunna. Their seats of Streatham and Tooting are combined into one.

• Major changes to the Chingford and Woodford Green seat held by Iain Duncan Smith, work and pensions secretary. Three strong Labour wards from Edmonton will be added to the seat, which becomes Chingford and Edmonton.

Tim Farron, Lib Dem MP for Westmorland and Lonsdale, will face a widely redrawn seat to be renamed Kendal and Penrith. This prompted speculation that Farron, seen as a future Lib Dem leader, would face a fight to remain in parliament. However, Tory sources feel the changes are gloomier for Rory Stewart, MP for neighbouring Penrith and the Border.

All MPs with English seats were given personal copies of the Boundary Commission for England report in parliament's Portcullis House at midday on Monday before its publication at midnight.

Separate reports by the commissions for Scotland, Wales and Northern Ireland will be released later.

MPs sat in groups in Portcullis House poring over maps of the changes that will see the number of constituencies cut from 533 to 502. Tory MPs, who had been led to believe by their party leadership that the review would favour their party, were involved in tense discussions with their whips about the changes, which went further than they expected.

"We are not happy about this," one senior Tory said. "There are MPs who gave up a lot to come here and now it looks like they face real fights. Whips have been coming up to us and asking how we are taking this. Not well is the message."

The MP said it was possible that the changes might be dropped. "This is far more wide-ranging than anyone had thought. It wouldn't surprise me if this is dropped. They'll just say it is all too complicated and they'll come back to it after the election."

Simon James, secretary to the Boundary Commission, told BBC Radio 4's Today programme that the proposals represented the most "significant change [to boundaries] for a generation". He admitted the shakeup had led to some "interesting results" but said the commission was constrained by the "very tight rules handed to us by parliament", which set limits on the size of the electorate within the new boundaries.

Downing Street sources said the prime minister, whose Witney constituency remains unchanged, was adamant that the changes will go ahead. The Tories and Lib Dems both pledged in their manifestos to cut the size of the Commons.

Cutting the number of seats from 650 to 600 is designed to save £12m a year and even up the size of seats. The Tories believe that Labour has an unfair advantage. The average size of the electorate in a Labour seat is 68,487, compared with 72,418 in Conservative seats. The average size of a Lib Dem seat is 69,440, mainly because it has proportionally more seats in Scotland where constituencies tend to be smaller.

Under the changes, a parliamentary constituency must have an electorate that is no smaller than 72,810 and no larger than 80,473. There will be exemptions.

The Isle of Wight, which has an electorate of just over 100,000 and is currently one constituency, is to be broken into two seats. Orkney and Shetland will be one seat. Na h-Eileanan an Iar, formerly the Western Isles, will remain as one seat even though it has an electorate of just over 20,000.

Tory, Labour and Lib Dem strategists were working late into the night to assess the impact of the changes. Sources said it would take time to make a proper assessment. But in initial conclusions the Tories feared they had been handed many more marginal seats, though that could work in Cameron's favour at the next election if there is a swing to the Conservatives.

The Lib Dems will face a challenge because changes to seats stretch the resources of a smaller party. But they point to the success of Sarah Teather, the education minister, who held on in the new seat of Brent Central.

None of the main parties commented publicly in detail on the Boundary Commission review but Ed Miliband criticised the government's plans to cut the size of the Commons. "We have serious concerns about the government's decision to change the boundaries, which we believe was an act of gerrymandering by the Conservative party," the Labour leader said. "However the Labour party now intends to take time to examine the initial proposals before making our formal response."

Pete Reeve, the Ukip local government spokesman, said: "It weakens the already tenuous link between the MP and his or her constituents. By increasing the size of the constituencies it will have the effect of pushing people away, rather than drawing them into the political process. Each MP will have to look after even more people, and there are precious few today who look after those they have very well."